let myName = '注册成功' // String 字符串
let age = " OK"
let result = myName + age
console.log(result)

let score = 100         // Number 数字
console.log(score)

let isFake = true       // Boolean true false
console.log(isFake)

let bag = undefined
console.log(bag)

let bag2 = null
console.log(bag2)

// let var const
let a1 = 'adafs'
console.log(a1)
a1 = 'sdf'
console.log(a1)  // 修改a1的内容